As described in the copending U.S. patent application Ser. No. 819,093 Joseph Leland Smith, entitled, MAGNETIZING APPARATUS AND METHOD FOR PRODUCING A STATICALLY CONVERGED CATHODE RAY TUBE AND PRODUCT THEREOF, filed concurrently herewith, and in the copending U.S. patent application Ser. No. 819,094 Joseph Leland Smith, entitled, MAGNETIZING APPARATUS AND METHOD FOR USE IN CORRECTING COLOR PURITY IN A CATHODE RAY TUBE AND PRODUCT THEREOF, filed concurrently herewith, a magnetic material is located adjacent a neck portion of an in-line color cathode ray tube. A magnetizing apparatus comprising various arranged and shaped conductors is placed next to the magnetic material. A magnetizing current of appropriate direction and peak magnitude is coupled to selected ones of the conductors, creating permanently magnetized regions within the magnetic material. The magnetic field produced by these regions move the electron beams in a predetermined manner to provide for static convergence and to establish the color purity of the three in-line electron beams.
It has been observed that with the elapse of time and the stress of the environment, such as temperature cycling and exposure to random stray magnetic fields, a small but undesirable amount of misconvergence and color impurity will appear corresponding to undesirable beam motions of up to 20 or more mils. It is desirable to create the magnetized regions within the magnetic material in such a manner that these undesirable beam motions will be eliminated.